BACKGROUND:
Succinylcholine remains the muscle relaxant of choice for rapid sequence induction (RSI) but has many adverse effects. High-dose rocuronium bromide may be an alternative to succinylcholine for RSI but recovery times are nearly doubled compared with a standard intubating dose of rocuronium. Magnesium sulfate significantly shortens the onset time of a standard intubating dose of rocuronium. We set out to investigate whether intravenous (IV) pretreatment with MgSO4 followed by a standard intubating dose of rocuronium achieved superior intubation conditions compared with succinylcholine.
METHODS:
Adults were randomized to receive a 15-minute IV infusion of MgSO4 (60 mg·kg–1) immediately before RSI with propofol 2 mg·kg–1, sufentanil 0.2 μg·kg–1 and rocuronium 0.6 mg·kg–1, or a matching 15-minute IV infusion of saline immediately before an identical RSI, but with succinylcholine 1 mg·kg–1. Primary end point was the rate of excellent intubating conditions 60 seconds after administration of the neuromuscular blocking agent and compared between groups using multivariable log-binomial regression model. Secondary end points were blood pressure and heart rate before induction, before and after intubation, and adverse events up to 24 hours postoperatively.
RESULTS:
Among 280 randomized patients, intubating conditions could be analyzed in 259 (133 MgSO4-rocuronium and 126 saline-succinylcholine). The rate of excellent intubating conditions was 46% with MgSO4-rocuronium and 45% with saline-succinylcholine. The analysis adjusted for gender and center showed no superiority of MgSO4-rocuronium compared with saline-succinylcholine (relative risk [RR] 1.06, 95% confidence interval [CI], 0.81-1.39, P = .659). The rate of excellent intubating conditions was higher in women (54% [70 of 130]) compared with men (37% [48 of 129]; adjusted RR 1.42, 95% CI, 1.07-1.91, P = .017). No significant difference between groups was observed for systolic and diastolic blood pressures. Mean heart rate was significantly higher in the MgSO4-rocuronium group. The percentage of patients with at least 1 adverse event was lower with MgSO4-rocuronium (11%) compared with saline-succinylcholine (28%) (RR 0.38, 95% CI, 0.22-0.66, P < .001). With saline-succinylcholine, adverse events consisted mainly of postoperative muscle pain (n = 26 [19%]) and signs of histamine release (n = 13 [9%]). With MgSO4-rocuronium, few patients had pain on injection, nausea and vomiting, or skin rash during the MgSO4-infusion (n = 5 [4%]).
CONCLUSIONS:
IV pretreatment with MgSO4 followed by a standard intubating dose of rocuronium did not provide superior intubation conditions to succinylcholine but had fewer adverse effects.
KEY POINTS
- Question: Does a combination of magnesium sulfate pretreatment followed by a standard intubating dose of rocuronium (0.6 mg·kg–1) produce superior intubation conditions to succinylcholine?
- Findings: For rapid sequence induction, a combination of pretreatment with magnesium sulfate followed by a standard intubating dose of rocuronium does not provide superior intubating conditions compared with succinylcholine but has fewer adverse effects.
- Meaning: In view of our findings, we hypothesize that for rapid sequence induction, a combination of pretreatment with magnesium sulfate and a standard intubating dose of rocuronium might be an alternative to succinylcholine in circumstances where succinylcholine administration is not warranted.
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